The present invention relates to a new and improved construction of gas-blast switch.
Generally speaking, the gas-blast switch of the present invention is of the type comprising a stationary contact element and a movable contact element. A blast nozzle is operatively associated with one of these contact elements. The blast nozzle has a blast channel which is freed, during the course of a cut-off stroke of the gas-blast switch, from the other contact element. At least one blast or blow-in opening is arranged transversely with respect to the extinguishing path and opens into the blast channel. The flow cross-sectional area of the blast or blow-in opening is less than that of the blast channel. Both the blast channel and also the blow-in opening are connected with a pump compartment containing an extinguishing gas which can be pressurized during the cut-off stroke.
Such gas blast switches are known, for instance, from U.S. Pat. No. 3,946,180, Swiss Pat. No. 522,284, particularly FIGS. 3 and 4, and German Pat. publication No. 2,710,868. The extinguishing gas-main stream formed in the blast channel during the course of a cut-off stroke of the gas-blast switch, is additionally placed into a turbulent flow by the extinguishing gas flowing out of the blow-in or blast-in opening, thereby improving the extinguishing characteristics of the gas-blast switch.
In any event, however, with the heretofore known gas-blast switches of the previously mentioned type this additional turbulence of the extinguishing gas flow is quite modest, because both the blast channel and also the blow-in opening are connected with one and the same pump chamber. The extinguishing gas located in the pump chamber, during the course of the cut-off stroke, is compressed. As soon as the blast channel frees the blast nozzle from the other contact element, the extinguishing gas flows out of the pump chamber especially through the blast channel itself. The amount of compressed extinguishing gas, flowing out of the blow-in opening, is comparatively small due to its smaller through-flow cross-sectional area and the velocity, with which this part of the extinguishing gas flows out of the blow-in openings, is only slightly greater than the flow velocity in the blast channel, because both the blast channel and also the blow-in openings so-to-speak "deplete" or "exhaust" compressed extinguishing gas out of the same gas supply.